Modern technology has produced a wide variety of image reproduction devices based upon different techniques for creating a hard copy. One technique which has become increasingly more popular due to its versatility is reproduction by an ink jet printer of an image derived by scanning a document. The ink jet printer in this system utilizes an array of small nozzles through which minute quantities of ink may be controllably expelled with sufficient force to coat a substrate upon which a reproduction is to be created.
Resolution and print speed are enhanced in current state of the art ink jet printers by incorporating a plurality of linear arrays of ink jet nozzles positioned so that the relative position of ink jets in adjacent arrays is staggered. Examples of this technique are contained in U.S. Pat. No. Re. 28,219 issued to R. P. Taylor et al on "Image Construction System Using Multiple Arrays Of Drop Generators" and U.S. Pat. No. 4,009,332 on "Memory Management System For An Ink Jet Copier".
The Taylor et al U.S. Pat. No. Re. 28,219 illustrates, as a principal embodiment, a configuration in which staggered ink jet arrays are driven by banks of photo-sensors which are directly coupled to the ink jets via amplification means. In this system, the original being copied is mounted on a drum having an internal illumination source and the photosensor banks are positioned adjacent to the outer periphery of the drum so that as the drum is rotated, translucent images create signal variations which are used to drive the associated ink jet arrays. This is a complex structure and the illumination technique diffuses the image and reduces resolution.
The Van Hook system disclosed in U.S. Pat. No. 4,009,332 processes electrical signals from a document scanner and stores the signals in a memory capable of activating individual nozzles on a predetermined and interlaced basis. The interlacing effect is enhanced by moving the nozzles relative to a rotating, copy receptor carrying drum so that the individual nozzles follow a diagonal track across the copy receptor.
The size of the originals which may be copied by current state of the art ink jet printers is limited by the size and placement of their photoelectric scanning arrays. For instance, in the Taylor et al patent the banks of photodetectors must be as wide as the copy being scanned. In systems such as that disclosed by Taylor et al, redundant photosensor banks are required to ensure proper overlapping of individual image areas to enhance resolution.
Further drawbacks are encountered by current state of the art ink jet printers due to their scanning arrangement whereby the image area of a single photosensor in a bank is controlled by the physical dimensions of the electronic device. This creates significant problems, including decreased resolution, when the printers are utilized to create enlargements of significant ratios such as are encountered when going from a microfilm copy to a standard sized document.
Prior to the present invention, ink jet printers used a great number of photosensors and ink jet nozzles to obtain blanket coverage of the original and copy receptor media to produce copy results of acceptable resolution.
Watkins, U.S. Pat. No. 3,632,871 on "Optical Scanning Device" is exemplary of current state of the art systems which use a rotating reflecting surface to direct an image onto a photoresponsive element.